科尔沁沙地梯级生态系统蒸散发规律及模型模拟研究

发布时间：2018-05-03 18:13

本文选题：科尔沁沙地 + 梯级生态系统　；参考：《内蒙古农业大学》2017年硕士论文

【摘要】：本文以科尔沁流动沙丘A4涡度数据为例,采用二次坐标旋转法(DR)和平面拟合法(PF)对水热通量、数据质量对比分析;选取科尔沁沙地梯级生态系统(流动沙丘-玉米地-草甸地-固定沙丘-半固定沙丘),结合2015年、2016年涡度相关系统实测的蒸散量,利用Shuttleworth-Wallace(S-W)模型对各生态系统蒸散量模拟分析,并进行适用性评价,得到的主要结论如下:(1)地形平缓区(180°-330°)垂直风速大于0,β在1.6773°左右;地形陡峭区(330°-180°)垂直风速小于0,β在-1.6486°左右;二次坐标旋转法和平面拟合法对潜热通量影响很大,分别增加17%和减小15%,二次坐标旋转法订正前后水热通量相关性均高于平面拟合法;二次坐标旋转法和平面拟合法订正后的数据分别有89.6%和89.3%通过湍流发展的充分性检验;摩擦风速由二次坐标旋转法订正前后的相关性高于平面拟合法;能量闭合率分别提高了 3.47%和2.78%;整个生长季中,6、8月订正后涡度数据质量有较好的提高。因此,二次坐标旋转法更适用于地面起伏较大的流动沙丘。(2)除流动沙丘外,各生态系统蒸散量呈明显的"钟型"分布,且随着夏季到秋季的变化,蒸散发的增强和减弱时间分别由6:00推迟到7:00、由19:00提前到18:00,增加减少的速率大小为玉米地草甸地固定沙丘、半固定沙丘流动沙丘;各站点植被"午休"现象导致蒸散量的减小量大小为固定沙丘、半固定沙丘草甸地玉米地,流动沙丘没有明显的植被"午休"现象。整体来说,蒸散量大小为:玉米地草甸地固定沙丘、半固定沙丘流动沙丘;降雨对各生态系统影响程度不同,在植被旺盛期为玉米地草甸地流动沙丘,在植被枯萎期为半固定沙丘草甸地固定沙丘流动沙丘。影响各生态系统实际蒸散发最显著的气象因素是Rn,不显著因素是θ。(3)日尺度上,S-W模型在玉米地的适用性高,流动沙丘则最低;且日尺度模拟精度低于小时尺度;小时尺度上,蒸散量模拟精度受天气影响,晴天高于阴、雨天,各生态系统适用性由高到低为:玉米地、草甸地、半固定沙丘、流动沙丘、固定沙丘;影响S-W模型最大的阻力和气象参数分别是冠层气孔阻力和净辐射、叶面积指数,最小的分别是冠层边界层阻力和土壤含水率;受阻力和气象参数影响最大的生态系统分别是草甸地和固定沙丘,最小的分别是半固定沙丘和草甸地。综上所述,S-W模型在科尔沁沙地中玉米地和草甸地的适用性更好。
[Abstract]:Taking the A4 vorticity data of Horqin flow dune as an example, the water and heat flux and data quality are compared and analyzed by using the quadratic coordinate rotation method (DRD) and the plane fitting method (PFN). The cascade ecosystem (mobile dunes, corn fields, meadow land, fixed dunes and semi-fixed dunes) in Horqin sandy land was selected. Combined with the measured evapotranspiration of the vorticity correlation system in 2015 and 2016, the evapotranspiration of each ecosystem was simulated by Shuttleworth-Wallace-S-Wmodel. The main conclusions are as follows: 1) the vertical wind speed is more than 0, 尾 is about 1.6773 掳, the vertical wind speed is less than 0, 尾 is about -1.6486 掳, and the vertical wind speed is less than 0 and 尾 is about -1.6486 掳. The quadratic coordinate rotation method and the plane fitting method have great influence on the latent heat flux, which increases by 17% and decreases by 15%, respectively. The correlation of the water and heat flux before and after revision by the quadratic coordinate rotation method is higher than that by the plane fitting method. 89.6% and 89.3% of the data obtained by the quadratic coordinate rotation method and the plane fitting method have passed the sufficient test of turbulence development, and the correlation of the friction wind speed before and after revision by the quadratic coordinate rotation method is higher than that by the plane fitting method. The energy closure rate increased by 3.47% and 2.78%, respectively, and the quality of vorticity data was improved better after the revised vorticity data in the middle of the growing season in June and August. Therefore, the quadratic coordinate rotation method is more suitable for mobile sand dunes with large surface undulation. Except for mobile sand dunes, the evapotranspiration of each ecosystem shows an obvious "bell" distribution, and changes with the summer to autumn. The increasing and decreasing time of evapotranspiration was delayed from 6:00 to 7: 00 and from 19:00 to 18: 00, respectively. The increasing and decreasing rate was fixed sand dunes in cornfield meadow and moving dunes in semi-fixed sand dunes. The reduction of evapotranspiration was caused by the phenomenon of "lunch break" in the vegetation of each station, the amount of evapotranspiration was reduced to fixed sand dunes, and there was no obvious phenomenon of vegetation "lunch break" in moving dunes in maize fields of semi-fixed sand dunes in meadow land. As a whole, the amount of evapotranspiration is as follows: fixed sand dunes and semi-fixed sand dunes in cornfield meadow; rainfall has different effects on each ecosystem, and in the period of vegetation exuberance, it is moving sand dunes in maize meadow land. In the period of vegetation withering, the moving dunes were fixed in semi-fixed dunes meadow. The most significant meteorological factor affecting the actual evapotranspiration of each ecosystem is Rn, and the non-significant factor is 胃. 3) the applicability of the model is high in cornfields on a daily scale and the lowest in moving dunes, and the accuracy of daily scale simulation is lower than that of a small scale, and the accuracy of daily scale simulation is lower than that of a small scale. The simulation accuracy of evapotranspiration is affected by weather. The applicability of each ecosystem from high to low is: corn field, meadow land, semi-fixed sand dune, mobile sand dune, fixed sand dune; The maximum resistance and meteorological parameters of S-W model were canopy stomatal resistance and net radiation, leaf area index, canopy boundary layer resistance and soil moisture content, respectively. The ecosystems most affected by resistance and meteorological parameters were meadow land and fixed sand dune, and semi-fixed sand dunes and meadow land were the smallest. In conclusion, the S-W model is more suitable for cornfield and meadow in Horqin sandy land.
【学位授予单位】：内蒙古农业大学
【学位级别】：硕士
【学位授予年份】：2017
【分类号】：Q14

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